Paper machine including a horizontal suction forming cylinder having multiple dewatering areas thereon

ABSTRACT

The paper machine comprises a horizontal cylinder, a slurry feed box opening onto the top side of the cylinder and the upper rim of the feed slice of which has been continued in order to form a roof-like upper lip between the feed slice and a feed roll placed on the cylinder at an approximate distance from the feed box in the direction of slurry flow, an endless felt or wire running from the feed roll along the cylinder towards the lower part of the same, an appropriate number of guiding and tension rolls for conducting said felt or wire back to the feed roll, a suction box or suction roll placed on the side of the feed roll opposite to that facing the cylinder and at the point where the slurry web and felt or wire depart from the cylinder surface, and possibly a compressed air box or equivalent placed above the felt or wire and after the feed roll, as seen in the direction of travel of the wire, approximately coincident with the gap remaining between the roof-like upper lip of the feed box and the wire. The horizontal cylinder is a suction cylinder which has therein a suction zone extending substantially from and including the upper roof-like lip continuously to the suction box or suction roll. The upper roof-like lip and suction cylinder form a first drying area for the slurry to form a partially dewatered web while the belt thereafter contacts the web against the surface of the suction cylinder over a major portion of the descending surface of the suction cylinder to form a second drying area in which suction and centrifugal force act upon the web to remove additional water.

June 20, 1972 E. A. NYKOPP 3,671,388

LUDING A HORIZONTAL SUCTION F0 PAPER MACHINE INC RMING CYLINDER HAVINGMULTIPLE DEWATERING AREAS THEREON Fnea July 18, 1969 2 Sheets Sheet lFig. 1

INVENTOE ERIK A. NYKOPF BY ATTORNEYS June 20, 1972 NYKQPP 3,671,388

PAPER MACHINE INCLUDING A HORIZONTAL SUCTION FORMING CYLINDER HAVINGMULTIPLE DEWATERING AREAS THEREON fi'lled July 18, 1969 2 Sheets-Sheet 2iNVENTOE ERIK ANYKOPF BYI 5 'ATTOIZNEYS United States Patent ice PAPERMACHINE INCLUDING A HORIZONTAL SUCTION FORMING CYLINDER HAVING MUL-TIPLE DEWATERING AREAS THEREON Erik A. Nykopp, Tampere, Finland,assignor to Oy Tampella AB, Tampere, Finland Filed July 18, 1969, Ser.No. 843,144 Int. Cl. D211? 1 /60; D21]: 1/06 US. Cl. 162-304 7 ClaimsABSTRACT OF THE DISCLOSURE The paper machine comprises a horizontalcylinder, a slurry feed box opening onto the top side of the cylinderand the upper rim of the feed slice of which has been continued in orderto form a roof-like upper lip between the feed slice and a feed rollplaced on the cylinder at an appropriate distance from the feed box inthe direction of slurry flow, an endless felt or wire running from thefeed roll along the cylinder towards the lower part of the same, anappropriate number of guiding and tension rolls for conducting said feltor wire back to the feed roll, a suction box or suction roll placed onthe side of the feed roll opposite to thatfacing the cylinder and at thepoint where the slurry web and felt or wire depart from the cylindersurface, and possibly a compressed air box or equivalent placed above'the felt or wire and after the feed roll, as seen in the direction oftravel of the wire, approximately coincident with the gap remainingbetween the roof-like upper lip of the feed box and the wire. Thehorizontal cylinder is a suction cylinder which has therein a suctionzone extending substantially from and including the upper roof-like lipcontinuously to the suction box or suction roll. The upper roof-like lipand suction cylinder form a first drying area for the slurry to form apartially dewatered web while the belt thereafter contacts the webagainst the surface of the suction cylinder over a major portion of thedescending surface of the suction cylinder to form a second drying areain which suction and centrifugal force act upon the web to removeadditional water.

BACKGROUND OF THE INVENTION Field of the invention The present inventionconcerns a paper machine in which a paper web is formed between arevolving cylinder and an endless felt or wire arranged to lap itssurface and which units may be provided, if desired, in multiple numberin succession for the purpose of'manufacturing a paper web of greaterthickness.

Description of prior art In the British Pat. No. 1,019,449 a compoundpaper machine and its unit have been described, comprising a horizontalrow of web-forming units, each unit consisting of a horizontal cylinderwith a flow box opening onto it, these boxes introducing slurry onto thecylinder surface, of a feed roll placed'upon the cylinder at anappropriate distance in the direction of slurry flow, of a companionroll placed to meet the cylinder at a point opposite to the feed roll onthe other side of the cylinder, and of a felt or wire net belt runningfrom the feed roll along the lower surface of the cylinder to thecompanion roll and which rims as an endless loop from one webformingunit to the next and back to the first unit again.

However, a paper machine system of this kind is only suitable for use inmultiple layer cardboard machines of comparatively low speed. With thismachine no high speeds can be attained because initial forming of theweb 3,671,388 Patented June 20, 1972 takes place on an open arcedsurface. As a consequence,

centrifugal force would, at high speeds, hurl fibres and water from theupper surface of the slurry layer away from the cylinder even in theevent that suction would be applied to the interior of the cylinder.

In the US. Pat. 3,132,990 a paper machine has been described comprisinga horizontal cylinder, a slurry feed box opening onto the ascendingupper surface of the cylinder, a feed box placed above the cylinderahead of the slurry feeding point and which cooperates with a suctionroll placed under the cylinder, to guide an endless wire so that it lapspart ofthe cylinder surface, and guiding rolls for returning the wirefrom the suction roll to the feed roll. In this paper machine the lowerand/or alternatively upper wall of the feed slice in the feed box aredisplaceable in their longitudinal direction in the direction towardsthe press nip for the purpose of regulating the slurry flow feed intothe press nip. This machine has the same drawback as that described inthe abovementioned British Pat. No. 1,019,449, and if the feed slice isplaced too close to the press nip, the excess water does not have timeto be drawn into the cylinder, instead of which it flows backwards alongthe cylinder surface or is thrown off by centrifugal force. The fiowalso tends to run off the ends of the cylinder between the wire andcylinder immediately after the feed roll. This occurs particularly athigh speeds, over about 250 m./min. The initial dewatering, which ishighly important, is also uneven in the crossmachine direction becausethe endless wire may stretch non-uniformly. Furthermore, the rate ofdewatering is not controllable at high running speeds. It is impossiblewith a paper machine of this kind to produce high-quality paper, andwhich is uniform in re spect of its base weight and fibre distribution,at high speeds, above about 250 m./min. The same is true for the secondembodiment presented in the said US. Patent, which includes means forshaping the press gap by the aid of elements placed above the wire, inwhich connection the :slurry feed box has been placed to open onto theascending upper surface of the cylinder. A great proportion of theslurry flow will be thrown off the cylinder surface or will rundownwardly away from the forming area, in this case along the suitableshaped, inclined upper surface of the forming box.

SUMMARY OF THE INVENTION The invention concerns a paper machinecomprising a horizontal cylinder, a slurry feed box opening onto thiscylinder for the feeding of slurry onto the ascending upper surface ofsaid cylinder, on the said cylinder at appropriate distance from thesaid slurry feed box in the direction of slurry flow a feed roll, andendless flexible wall running from this feed roll along the surface ofsaid cylinder towards the lower part of the cylinder, an appropriatenumber of guiding and tension rolls which conduct the said flexible wallback to the said feed roll, and a suction device, which is located onthe side opposite to the cylinder of the said feed roll at the pointwhere the slurry web and the said flexible wall are separated from thesurface of said cylinder.

The aim of the present invention is to afford comparatively inexpensiveequipment for the manufacturing, employing high speeds, of high-qualitypaper and which is uniform in respect of its base weight and fibredistribution, e.g. newsprint.

A further object of the invention is to afford a compound paper machinecomprising a plurality of mutually cooperating devices according to theinvention for the purpose of forming a multilayer slurry web.

In a paper machine according to the invention, the upper rim of the feedslice of the slurry feed box has the feed slice and feed roll.

When the slurry flow arrives on the surface of the cylinder, water isdrawn from it, and by action of the rooflike, appropriately shaped upperlip a comparatively long enclosed area is produced where the hydraulicdifferential pressure between the upper surface of the slurry web whichis formed and the suction cylinder is as high as possible, whichcircumstance has an equalizing effect with regard to base weight becausethe slurry tends to flow to points where filtration is easy, that is, topoints where fibres are less abundant. The influence of centrifugalforce has also been eliminated at the most critical of all webformingphases, namely, in its initial phase. Furthermore, the dewatering rateof slurry within the long enclosed area of first drying area can beregulated With the aid of the upper lip, the shape of which ischangeable as may be desired. It is also possible to seal the edges ofthe forming area roofed over by the upper lip and thus to prevent thewater from running off the cylinder at its ends. The web arrives in thepress nip between the endless wire and the cylinder, as viewed from theside, as a comparatively narrow flow and which is of uniform baseweight, and in a condition of considerably higher consistency than inthe initial part of the forming area. The dewatering rate is adjustableby means of the vacuum in the suction device, of the profile of theupper lip, and by changing the gap between the trailing end of the upperlip and the cylinder. The partly dried web coming from under theroof-like upper lip is no longer highly susceptible to effects ofcentrifugal force. As a result, it is possible with a device accordingto the invention to produce a slurry web at far higher speeds than withdevices belonging to previous art, for instance at speeds in excess ofabout 250 m./min.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in closerdetail in the following, with reference to the attached drawings, inwhich FIG. 1 presents a schematic elevational view of a paper machineaccording to the invention, and FIG. 2 shows a similarly schematic sideelevation of a particularly advantageous embodiment of the invention.

FIG. 3 shows a compound paper machine for forming a multilayer slurryweb.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, thereference numeral 1 indicates the slurry feed box, 2 is the cylinder, 3is a flexible, porous endless belt which is advantageously an endlesswire or felt, 4 is the feed roll, 5 is a suction box, 6 is the roof-likeupper lip, 7 is the slurry feed slice, 8 is a pick-up felt, 9 is apick-up roll, 10 is a save-all, and 11 is a jet pipe for cleaning thecylinder. 7

The slurry flow arrives from the feed slice 7 onto the surface of thecylinder, at which stage water is drawn from it and by virtue of theroof-like upper lip 6 and of seals placed on the sides between the upperlip and the cylinder, an enclosed area or first drying area is formed inwhich the hydraulic differential pressure between the upper surface ofthe slurry Web that is being formed and the suction cylinder is as highas possible, whereby favour-' uniform web which was already produced,and reduces the one-sided structure of the web, while at the same timeefficient dewatering takes place in two directions. The dewateringregion when the paper is between the wire "3' and the cylinder 2 is thesecond drying area encountered by the paper web as it is formed upon thecylinder 2.

Upon arriving on the lower part of the cylinder, the slurry web ispicked off the cylinder with the aid of a suction box 5 or equivalent,to continue its travel upon a plane wire, from which it is taken off,e.g. with the aid of a pick-up arrangement 8, 9 to be conveyed onwardfor further treatment. At this point the wire 3 is returned to the feedroll 4 over appropriate guiding and tension rolls.

The slurry web may also be carried along with the wire to the nextmachine, which is a replica of the first machine described above, andfrom the second machine further to a third machine, etc., depending onthe thickness of the slurry web or its number of layers which isdesired. In the last machine, the web is picked up from the wire inconventional manner and conveyed onward for further treatment, and thewire is carried back to the feed roll 4 of the first machine.

It has been observed, whenever the web speed exceeds about 250 m./min.,that no longer is any water drawn into the suction box of the suctionroll, instead of which the water remains in the perforation of themantle and from which it is hurled out after the suction zone has beenpassed. It is advantageous for this reason to place the save-all 10after the suction box 5, and at the same time it serves the purpose ofcollecting the water coming from the nozzle 11, by means of which thecylinder is flushed.

It is to be understood that dewatering of the web be further augmentedon the plane wire run, by providing adjacent to this run and before thepick-up arrangement dewatering elements of a kind previously known initself, such as suction boxes.

The device presented in FIG. 2 differs from the foregoing in that overthe wire 3 and after the feed roll 4 in the direction of travel of thewire there has been placed a compressed air box 12 coincident with thegap remaining between the roof-like upper lip 6 of the feed box 1 andthe wire 3. Upon emerging from under the upper lip 6, the slurry web issubjected to the pressure of the air discharging from the compressed airbox 12 and through the wire 3, whereby in spite of the influence ofcentrifugal force the fibres and water in the upper surface of theslurry web cannot be detached from the web and, on the contrary, remainwhere they are, while at the same time this external pressure aids thedewatering into the suction cylinder 2.

FIG. 3 shows a compound paper machine for making a multilayer paper web.This machine has a first web former A and a second web former B, eachweb former being of the type shown in FIG. 1. The endless belt C isconducted from the preceding web former A to the feed roll D of the nextweb former B. After the belt leaves 'web former B, it returns to webformer A.

What is claimed is:

1. A web-forming apparatus comprising:

a rotatable, horizontally mounted suction cylinder;

a slurry feed box with a feed slice for depositing slurry upon theascending surface of said rotatable cylinder, said feed slice having anupper lip extending over said ascending surface and in close proximitythereto, said upper lip solely with said ascending surface forming asubstantially enclosed area between said lip and said ascending surfaceof said cylinder for containing said deposited slurry, said enclosedarea forminga first drying area wherein the suction of said suctioncylinder removes a portion of the water in said slurry to form apartially dewatered Web;

a flexible, endless belt positioned to contact said partially dewateredweb at a point immediately adjacent to said upper lip, said contactbeing made as said partially dewatered web emerges from under said upperlip, said belt maintaining said partially dewatered web against surfaceof said suction cylinder over a major portion of the descending surfaceof said suction cylinder, providing a second drying area in which thesuction and centrifugal force upon said partially dewatered web removesadditional water from said partially dewatered web in two directions;and

a suction box disposed on the side of said endless belt opposite saidpartially dewatered web and located at substantially the point at whichsaid endless belt and said partially dewatered web are separated fromsaid cylinder wherein said suction box provides a force to separate saidpartially dewatered web from said cylinder, the suction cylinder havingtherein means defining a suction zone extending substantially from andincluding the first drying area, through the second drying area, andsubstantially to the suction box where the web is separated from thecylinder.

2. The web-forming apparatus of claim 1 additionally comprising:

an air blowing means positioned on the side of said endless belt whichdoes not contact said partially dewatered web, said air blowing meansbeing further positioned to permit air to be blown through said endlessbelt and against said partially dewatered web as it emerges from undersaid upper lip, said air blowing means for providing a force to maintainsaid partially dewatered web in contact with said suction cylinder whensaid partially dewatered web upon said cylinder is between said upperlip and the point of contact with said endless belt.

3. The web-forming apparatus of claim 1 wherein said endless belt iscomprised of wire.

4. The web-forming apparatus of claim 1 wherein the endless belt iscomprised of felt.

5. The web-forming apparatus of claim 1 wherein said suction cylinderhas a suction opening coextensive with the portion of contact of saidpartially dewatered web with said suction cylinder.

6. The web-forming apparatus of claim 1 additionally comprising:

a Water spraying means for spraying water upon the surface of saidcylinder over the portion of said cylinder not containing said partiallydewatered web; and

a collection means for collecting said sprayed water.

7. The web-forming apparatus of claim 1 additionally comprising:

at least one additional rotatable, horizontally mounted suctioncylinder;

an additional slurry feed box for each additional cylinder, each saidadditional feed box with a feed slice for depositing slurry upon theascending surface of the additional cylinder, said feed slice having anadditional upper lip extending therefrom, said upper lip forming anenclosed area between said lip and said additional cylinder forcontaining the additionally deposited slurry, said enclosed area forminga first drying area for each said additional cylinder wherein thesuction of said suction cylinder removes a portion of the water in saidadditionally deposited slurry to form an additional partially dewateredweb; and

wherein said endless belt is positioned to additionally References CitedUNITED STATES PATENTS 2,772,606 12/1956 Kelly 162-276 2,995,186 8/1961De Montigny 162-317 X 3,072,180 1/1963 Jodrey 162-347 X 3,111,45411/1963 Tucker et al. 162-297 3,132,990 5/1964 Trufitt 162-317 3,321,3605/1967 Holt 162-317 X 3,472,733 10/1969 Holt 162-214 X 3,485,71512/196'9 Kobayashi 162-304 S. LEON BASHORE,

Primary Examiner A. DANDREA, 111., Assistant Examiner US. Cl. X.R.

